Method of manufacturing paper pulp



Patented Nov. 16, 1937 PATENT OFFICE METHOD OF MANUFACTURING PAPER PULP Edwin P. Jones, Garden City, N. Y., 'assignor to Champagne Paper Corporation, New York, N. Y., a corporation of New York No Drawing.

1 Claim.

' tremely coarse fibers to extremely" fine fibers.

The term coarse fibers is to be understood as not necessarily coarse in diameter, though this is usually the case, but is to be understood as meaning a fiber produced by either a chemical or a mechanical process in which but a relatively small percentage of the shives have been removed. This is particularly true of that class of rags made from so-called crash toweling where the character of the goods to be made does not require 1 that the major portion of the shives be removed. The term fine fibers is to be understood as apply-' ing to the fibers in which a considerable percentage of the shives have been removed, such fibers being used in the manufacture of relatively fine fabrics, such 'as lawns, handkerchiefs,

etc.

Linen rags constitute an important source of material for the manufacture of paper, but in order to obtain a base material for the manufacture of paper of very high grade, it is essential that the rag stock be subjected to a method of treatment whereby not only is the major portion of the shives removed, but that portion of the shives which remains after practically any treatment is rendered invisible and innocuous, to

the extent that the presence of such shives will have no deleterious effect on the quality of the paper to'be produced therefrom.

In my present invention I have devised an improved method or process'for treating linen rag stock to remove therefrom the greater percentage of the shives and to render harmless the percentage of shives remaining after treatment.

A feature of my invention is an improved meth- '0d of producing a high grade bleached pulp or paper stock from linen rags.

In carrying out my invention I place the rag stock in a digester, preferably a rotary digester, and of conventional design and cook the same under the following conditions:

(1) The amount of water used in the digester may vary between approximately 2%; to 4 times the dry weight of the fiber;

(2) The temperature during the cooking may vary between approximately and centigrade, the temperature corresponding to a gauge pressure'between approximately 30 and 85 pounds per square inch;

Application October 16, 1936, Serial N0. 105,915 A (3) The cooking ti in the digester may vary between 5 to 8 hours;

(4) To the mixture of water and fiber in the digester chemicals are used consisting of a mixture of calcium oxide and sodium carbonate in -5 the appropriate proportions in which such chemicals react to liberate sodium hydroxide, and sulphur is added in the proportions of from 1% to 4%, it being understood that the percentage of the chemicals employed has reference to the percentage of the chemicals as based upon dry weight of the fiber under treatment.

The chemicals employed are utilized in the following proportions based upon dry weight of the fibers under treatment: l5

, Percent Calcium oxide -J 4to 10 Sodium carbonate 12 to 20 Sulphur lto 4 These proportions 6f the'various chemicals employed will vary in accordance with the physical characteristics of the rag stock being treated and such physical characteristics are readily determined from a visual inspection of the rag stock, although in some instances it may be desirable to determine the physical characteristics by a chemical analysis. As an excess of calcium oxide 'is undesirable because of the subsequent difficulty in bleaching the fiber after digesting, it is desirable to use a slight excess of sodium carbonate, and the percentages as given above are determined with this object in view.

After the digesting operation has been completed the digester is blown and the digested fiber is washed to remove excess shive as well as to remove the impurities in the fiber which have been rendered -water soluble by the digesting process.

pounds, as such oxycellulose or related compounds 45 impart special desirable properties to the paper to be ultimately made from the bleached pulp.

The process and method as above described, produces a high grade bleached pulp from which an extremely high grade of paper may be manu- 50 factured and in which paper there is a minimum of'shives, and also in which such shives as are present are invisible and do not materially affect the grade of paper produced.

The proportions of the chemicals employed 55 from the minimum amounts as above set forth will be increased to the maximum as the percent'age of shive fiber in the rag stock increases.

Whereas I have described my invention by reference to specific forms thereof, it will be understood that many changes and modifications may be made without departing from the spirit of the invention.

I claim:

That improved method of producing bleached.

pulp from linen rags, which consists in sub- EDWIN P. JONES. 

